Extracellular matrix, integrins, and Notch signaling mechanism are conserved between a wide variety of multi-cellular creatures from sponges to man and under normal conditions are critical for maintaining cellular homeostasis. Conversely, under pathological conditions, extracellular matrix, integrins, and Notch signaling are collectively associated with a wide variety of human pathologies including but not limited to tumor angiogenesis, growth, invasion, and metastasis. Our preliminary results have discovered a previously unidentified signaling mechanism that couples extracellular matrix to altered Notch signaling via RGD binding 3 and 6 integrins. Therefore, the main hypothesis of this proposal is that RGD containing molecules in the extracellular matrix negatively impact Notch signaling by ligating 3 and 6 containing integrins. The main goal of this proposal is to examine this hypothesis from four different angles with four complementary specific aims. In aim 1, we will dissect the mechanistic basis by which 3 and 6 integrins suppress Notch signaling. In aim 2, we will identify integrin binding partners for and 6 integrins that cooperate to suppress Notch. In aim 3, we will determine if all RGD domains of pro- and anti-angiogenic extracellular matrix proteins are equally capable of suppressing Notch signaling. In aim 4, we will determine if 3 and 6 integrins suppress signaling from all Notch receptor/ligand combinations or if specific Notch receptor/ligand combinations are preferentially suppressed. By addressing these four aims, this proposal will dissect the basic parameters of a completely novel cell signaling mechanism that will have a broad impact on our understanding of normal and disease processes that as associated with extracellular matrix, integrins and Notch signaling. By addressing the basic parameters of this signaling mechanism, this proposal will lay the foundation for future research that will address the biological significance of this mechanism to cancer and angiogenesis. PUBLIC HEALTH RELEVANCE: Extracellular matrix, integrins, and Notch signaling are collectively involved in regulating an incredible diversity of events in normal and pathological cell physiology. Based on our preliminary data, we hypothesize that extracellular matrix controls Notch signaling via 3 and 6 integrins. The experiments described herein will explore this hypothesis and in so doing, will make a tremendous impact on our understanding of how extracellular matrix, integrins, and Notch signaling cooperate to control not only normal cell biology but also pathological cell biology associated with diseases such as cancer.